The invention concerns a rotary or pivotal unit having a drive as well as a method for operating thereof. The rotary or pivot unit comprises a working piston which is housed in a cylinder of a housing and can be loaded by fluid pressure media, as well as displaced in an axial direction.
Rotary or pivotal units of this type and their associated drives are widely used in automation systems, since they have a very high power density due to the fluid, in particular, pneumatic pressure media. The working piston may thereby be operatively connected, via a rotational coupling, to a pivot member which is borne to rotate within the housing. The motion of the piston in an axial direction thereby pivots the pivot part. The pivot part may e.g. have gripping means for gripping and pivoting workpieces.
Shock absorbers are conventionally used to move the piston to a certain target position to decelerate or delimit the linear motion of the working piston in the axial direction. The use of shock absorbers has many disadvantages. In particular, the shock absorbers cannot withstand the high loads at high pressures, and are disadvantageously subject to wear. For this reason, shock absorbers cannot provide reproducible damping rates on a long-term basis.
Shock absorbers are also relatively expensive, occupy space in or on the drive and restrict the power of the drive.
The use of shock absorbers is also disadvantageous in that the piston or the load moved by the drive cannot be moved to any position and can therefore not be disposed at any position. Positioning therefore requires appropriate mounting of a shock absorber or associated stop at a certain location. The position of the shock absorber or stop must therefore be changed to change positioning. The above-described conventional drives therefore lack flexibility.
It is the underlying purpose of the present invention to further develop a rotary or pivotal unit of the above-mentioned type which ensures high power density and increases the positioning capability and thereby the flexibility of the drive.